Apparatus and Process for Preventing Printed Film Distortion during Heat Shrinking

ABSTRACT

This invention is directed preventing or reducing the print distortion in a heat shrink tunnel. This problem was be solved by isolating the printed area on the film from the hot air in a heat tunnel. The isolation reduces the shrinkage of the printed area so that the print distortion is minimized

FIELD OF THE INVENTION

This is invention is related to preventing distortions of print on a heat shrink film during heat shrinking.

BACKGROUND OF THE INVENTION

The prior art has used bands of paper or light cardboard to wrap products to keep the products together. For example, the band can keep a lid from separating from a container. The bands usually are printed with advertisements and logos. The band is usually narrower than the than the width of the product Using heat shrink film with print to form the bands causes the print to be distorted during heat shrinking process. Usually a flap of the film is pushed on a conveyor and a product is wrapped with the film causing a overlap at the bottom of the product. A heat shrink machine shown in U.S. Pat. No. 7,836,670 issued on Nov. 23, 2010 invented by Alain Cerf is incorporated by reference in the entirety to show the operation of a lap seal heat shrink machine having a overlap at the bottom.

SUMMARY OF THE INVENTION

The problem with the print distortion can be solved by isolating the printed area on the film from the hot air in a heat tunnel. The isolation reduces the shrinkage of the printed area so that the print distortion is minimized

BRIEF DESCRIPTION OF THE DRAWING

The single figure shows articles moving through a heat tunnel with a heat shield over the articles.

DETAILED DESCRIPTION OF THE INVENTION

The drawing shows a side view of a product 1 which can be bundle of articles or a single article film wrapped with a printed heat shrinkable film to form a band having a print area on the top of the product. A tunnel conveyor 3 moves the product through a heat tunnel 2. The preferred embodiment has a belt 4 moving through the heat tunnel on a upper conveyor 5 to isolate the print area on top of the product from the hot air in the heat tunnel to reduce the distortion of the print area. The belt can be made of silicone or Teflon. The belt moves at about the same speed as the tunnel conveyor 3. By moving the belt at about the same speed, the belt can rest on the top of the product while the product moves through the heat tunnel thereby preventing or reducing the film with the print area from heat shrinking. The shrinkage on the sides and bottom of the container creates enough tension for the band to be tight.

The conveyors can be moved and synchronized using conventional techniques in the prior art.

Other alternatives can be used to isolate or reduce the hot air from distorting the print area of the heat shrink film. Isolation barriers such as a plate located about 5 mm above the product would also reduce the heat shrinkage of the printed area of the film. Also an additional benefit occurs when the belt rest on the product causing a better lap seal. 

1. An apparatus for reducing or eliminating print distortion of a product wrapped with printed heat shrink film in a heat shrink tunnel comprising means for heat shrinking a printed film wrapped around a product moving on a conveyor, means for isolating a printed area of the film from the heat to prevent or reduce the heated shrinkage of the print area.
 2. An apparatus according to claim 1 wherein means for isolating includes a moving belt that covers the print area.
 3. An apparatus according to claim 2 having means for moving the belt at about the same speed as the product on the conveyor thereby allowing the belt to rest on the product.
 4. An apparatus for reducing or eliminating print distortion of a product wrapped with printed heat shrink film in a heat shrink tunnel comprising means for heat shrinking a printed film wrapped around a product moving on a conveyor through the heat shrink tunnel, and means for isolating a printed area of the film from the heat during heat shrinking to prevent or reduce the heated shrinkage of the print area by moving a belt at about the same speed as the product moving on the conveyor.
 5. A process for reducing or eliminating print distortion of a product wrapped with printed heat shrink film in a heat shrink tunnel comprising heat shrinking a printed film wrapped around a product moving on a conveyor through the heat shrink tunnel, and isolating a printed area of the film from the heat to prevent or reduce the heated shrinkage of the print area.
 6. A process according claim 5 including a belt moving at about the same speed as the product moving on the conveyor for isolating a printed area of the film from the heat during heat shrinking.
 7. A process according claim 6 wherein the belt rests on the product thereby covering the print area.
 8. A product produced by the process of claim 5
 9. A process according to claim 5 wherein the heat shrink film forms a band around the product. 